The use of information carrier plates (also referred to as phosphor or phosphor storage plates) for obtaining visually perceptible contrast upon exposure to X-rays is known in the art as computed radiography (CR) and is described for example in U.S. Pat. No. 7,211,785 (Berger).
The imaging cycle employing such plates comprises juxtaposing the plate nearby a specific part of the body (e.g., leg, arm, tooth, and the like) and then exposing the plate to X-rays in order to obtain an image from stored radiation energy. Following exposure, the plate is then removed from the patient and the latent image that is stored thereon is scanned by a laser beam or other energy source to stimulate emission of the stored energy and to form corresponding image data from the emitted energy. After the plate has been scanned, the obtained image data can be displayed and stored for further examination. The exposed and scanned plate is then erased and can be reused in a subsequent imaging cycle.
It can be appreciated that each plate must be properly tracked throughout the imaging cycle as the plate circulates from X-ray exposure, to scanning, to erasure, and to re-use. That is, it must be possible, at each stage in this process, to know specific plate identification information as well as patient identification information and identification information concerning specific treatment with which a plate is associated.
This requirement is important for general medical computed radiography (CR) and becomes especially complex for intra-oral dental computed radiography applications. In dental clinics, large numbers of patients undergo X-ray examination, and therefore a large number of information carrier plates can be in circulation at any one time, thus increasing the probability for mismatch between a particular plate and the patient and treatment data associated with the plate, as well as with the obtained image on the plate. The probability for mismatch is especially high in a working environment where several treatment rooms, each equipped with an X-ray generator, share the same scanning device. Any mismatch can result in confusion, delay, waste, incorrect diagnosis, and the need to repeat an exposure in some cases. Other possible errors that can occur due to mismatch include inadvertent re-exposure of a plate that has not yet been erased.
The likelihood for error and the impact of an error can be further compounded when a full mouth scan is executed. This dramatically increases the number of plates used for a particular patient and requires careful tracking to avoid mistakes.
With intra-oral dental computed radiography, the mismatch between CR plates is not easily detectable to the eye, since different teeth can have a relatively similar appearance. The likelihood of confusion is high when compared with other medical radiography applications that image larger or more distinctive parts of the body about which there can be much less confusion.
Thus, positive and unequivocal identification, as well as monitoring and tracking of information carrier plates, is desired in computed radiography in general, and in intra-oral dental computed radiography in particular, since it helps to prevent patient mismatch and other errors.
There have been a number of attempts to address this problem.
One example can be found in U.S. Pat. No. 5,428,659 (Renner) disclosing digital memory configured as a PCB (printed circuit board).
In intra-oral dental computed radiography, the exposed information carrier plates are usually placed on a flat holder that is divided into cells referring to different teeth. A technician puts the CR carrier plates on the holder such that a certain plate occupies a certain cell. The pattern of the cells corresponds to the pattern of a template that is filled in by the dental practitioner before submitting the plates to X-ray exposure. The plates are moved from the treatment station to an X-ray station and then to a scanning station, lying on the holder in the order corresponding to the template pattern. In particular situations, this arrangement can be unreliable, for example, the plates can fall from the holder during handling. Their correct re-attribution to the corresponding cell can be complicated if the plates are not provided with some type of identification means.
Radio Frequency Identification Devices (RFID devices) are known for identification, tracking, and monitoring of various items. RFID tracking is used for identifying various items, like consumer goods, reusable and disposable items, people, animals and the like. This identification technology has been implemented in various technical and non-technical fields, including medicine.
An RFID system comprises two main components: (i) a transponder associated with an item to be identified, and (ii) an interrogator, separated from the transponder by a short distance, that comprises an antenna, a transceiver and a processing device. The interrogator component sends RF energy and an interrogating signal (if necessary) to the transponder and then receives an RF response signal from the transponder. The received signal is transferred to the processing device and is read.
The transponder, or so-called RFID tag, is affixed by a suitable method to the item to be identified and comprises an integrated circuit containing RF circuitry. This circuitry serves as memory for storing information to be transmitted as a signal to the processing device in the interrogator. The RFID tag also comprises an antenna for transmitting this signal. Reading the signal that has been sent by the transponder allows the item bearing the tag to be identified and monitored.
There have been attempts to implement this technology in computed radiography. Some examples are noted below.
U.S. Pat. No. 7,319,396 (Homanfar) and U.S. Pat. No. 7,518,518 (Homanfar) describe using an RFID tag.
U.S. Pat. No. 7,095,034 (Haug) describes image carriers enclosed in cassettes, with an RFID tag affixed to the edge region of the cassette.
U.S. Pat. No. 5,418,355 (Weil) describes storage media enclosed in a cassette wherein the media is provided with an identification bar code.
U.S. Pat. No. 4,739,480 (Oono) describes a label adhered to the image storage panel, with the panel stored in a cassette. The information carried by the label represents an identification code assigned to the panel.
U.S. Pat. No. 6,359,628, U.S. Pat. No. 5,757,021 (Dewaele) and EP Patent No. 0727696 (Dewaele) describe media contained in a rigid cassette with an RFID tag attached to a specific location on the cassette.
U.S. Pat. No. 4,960,994 (Muller) describes media that is used in association with a cassette and with a memory affixed to the cassette in a predetermined location.
U.S. Pat. No. 6,381,416 (Manico) describes use of an RFID tag in association with photographic film used in consumer photography, for example, for establishing conditions to be selected for processing of the film.
U.S. Pat. No. 8,374,461 (Humphreys) describes a digital radiography plate identification system.
U.S. Patent Application No. 2012/0019369 (Taskinen) describes an arrangement for controlling image plate and its image information and a method for controlling the arrangement.
U.S. Pat. No. 6,826,313 (Robar) describes a method and automated system for creating volumetric data sets.
U.S. Patent Application No. 2009/0212107 (Crucs) describes an auto-distribution of scanned digital images based on standardized identifiers.
U.S. Pat. No. 6,359,628 (Buytaert) describes combined identification and preview system for use in digital radiography.
U.S. Pat. No. 7,775,713 (Klemola) describes an arrangement for dental imaging.
While such solutions may employ RFID devices to help support the use of X-ray cassettes, however, there can be little or no improvement to the workflow process for dental imaging with these solutions. Persistent problems such as inconsistent labeling of plates, poor tracking of plate usage, and potential mismatch of images to patients continue to impede workflow efficiency in large dental practices.
Thus, despite attempts to employ RFID technology with various types of imaging media, there is room for improvement in providing an RFID solution tailored for specific workflow requirements of intra-oral dental computed radiography.